Base station devices, standardization of which are currently in progress by 3GPP (3rd Generation Partnership Project), include: an (e)NodeB that serves macrocells (normal cells); and a Home (e)NodeB (Home (e)NB) that serves cells smaller than the macrocells. Cells served by the Home (e)NodeB include: an open cell to which all users are allowed access; a CSG cell (Closed Subscriber Group cell) which allows specific users to access thereto; and a hybrid cell having both characteristics of the open cell and the CSG cell. Requirements for the CSG cells are defined on the eighth section of Non-Patent Document 1.
A CSG_ID, which is unique identification information, is assigned to a CSG cell. According to Non-Patent Document 1, it is necessary to support at least 125 million CSG_IDs in PLMN (Public Mobile Land Network).
However, the number of CSG_IDs to be found in the PLMN by a terminal of a user is generally considered to be not so great. It is necessary for the terminal to determine whether or not the found CSG cell is an accessible cell. At this time, the terminal uses a CSG list (allowed CSG list) that is a list of accessible CSG cells and is stored in the terminal. The number of CSG cells varies over time. For this reason, it is necessary for the terminal to always have the latest list.
Non-Patent Documents 1 and 2 define the CSG list as follows.                The CSG list is stored in a USIM (Universal Subscriber Identity Module Card) of a UE (User Equipment: mobile communication terminal).        The CSG list is updated individually for each UE (the details of update procedures and update timings are not defined).        Information (CSG_ID, operation frequency, PCI (Physical Cell Identity), etc.) of CSG cells placed in a macrocell (normal cell) is managed by operators.        If a Home (e)NB is newly placed, operators can know the position thereof.        